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Starter Questions

Starter Questions. Day 1 Which wave has more energy? Which wave has more energy?. A. B. A. B. Starter Questions. Day 2 How does amplitude affect sound? How does wavelength affect sound?. Wave Properties of Light & Sound. Waves In General.

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Starter Questions

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  1. Starter Questions Day 1 • Which wave has more energy? • Which wave has more energy? A B A B

  2. Starter Questions Day 2 • How does amplitude affect sound? • How does wavelength affect sound?

  3. WavePropertiesof Light & Sound

  4. Waves In General • Waves are a propagation of energy through a medium (material) • Waves depend on elasticity of the material • A wave passing through the medium applies an alternating unbalanced force to each molecule causing it to vibrate around its equilibrium or “rest” position.

  5. Waves In General: • Waves are a propagation of energy traveling through a “medium” (material) • Properties of waves depend on elasticity of the medium: As you can see, sound travels at different speeds depending on the medium Think: Why would waves move through solids faster than a gas like “air”?

  6. Anatomy of a wave Crest Equilibrium (Rest) Position Node λ Trough

  7. Amplitude Amplitude: The "height" of a wave when viewed as a graph. (Also note that high amplitude = high energy.) A shape If I wanted to increase the amplitude, I simply increase its height.

  8. Amplitude Amplitude = Loudness = Volume Higher amplitudes are interpreted as a higher volume, hence the name "amplifier" for a device which increases amplitude.

  9. Wavelength Wavelength: The length of the wave. λ(Lambda) Arm λ If I wanted to make the wave bigger, I simply stretch it.

  10. Frequency Arm Flapping Frequency: The number of waves in one second. Measured in kilohertz (Khz), or cycles per second. The faster the sound source vibrates, the higher the frequency. ν(Nu) ν = λ/s 1 second

  11. Frequency Arm Flapping Frequency: The number of times the wavelength (λ) occurs in one second. Measured in kilohertz (Khz), or cycles per second. The faster the sound source vibrates, the higher the frequency. ν(Nu) ν = λ/s 1 second

  12. Frequency Frequency: The number of times the wavelength (λ) occurs in one second. Measured in kilohertz (Khz), or cycles per second. The faster the sound source vibrates, the higher the frequency. ν(Nu) ν = λ/s ν = λ/s [Hz] 1 second

  13. Frequency Frequency = Pitch = Note = Tone Higher frequencies are interpreted as a higher pitch. For example, when you sing in a high-pitched voice you are forcing your vocal chords to vibrate quickly. (Also note that high frequency = high energy.) Our ears are sensitive to sound energy. We perceive a high frequency as a high pitched note; a low frequency as a low pitched note.

  14. Light Spectrum Light Frequency = Type of light and color Our eyes are sensitive to light energy. We perceive a low frequency light as red or yellow and a high frequency as blue or violet.

  15. White Light? White Light is actually made up of many different colors – each color is made up of its own frequency and wavelength. When you combine the colors together it actually makes White light! You can shine white light into a prism and it separates it out into the mix of colors

  16. Notice the white light coming in Notice the split spectrum coming out.

  17. Types of Waves • Transverse (Shear) Waves • Longitudinal (Compression – Sound) Waves • Surface Waves – wave’s that move in a circular motion on the surface • (We will learn more about these during our geology unit.)

  18. Transverse (Shear) Waves Shear waves move perpendicular to the equilibrium point

  19. Longitudinal (Compression) Waves Longitudinal waves stretch (decompress) and compress the bonds between molecules back and forth in the same direction the wave is moving.

  20. How do waves propagate away from its source?2 Dimensionally or 3 Dimensionally

  21. Propagation of Waves The layers of an onion, are a good representation of how waves look as they travel In every direction equally at the same time! HEY! I’ve got layers too!!! Except for surface waves, waves propagate outward spherically in 3D - like the layers of an onion.

  22. If the Wave propagated out on a separate 2D plane, I wouldn’t see it. Wave hitting my eye – I can see it! If waves propagated in only 2D like waves on a pond, then if we moved the candle up a little higher we wouldn’t be able to see it.

  23. Since waves propagate in 3D, we can see the light from this candle in all directions. Same thing applies with sound.

  24. Wave Propagation is like an Onion - its relationship to Intensity Intensity: The further out you go from the source, the less intense the wave is. If you wanted to save your ears from the loudness of the speakers – scoot back!

  25. Why we see something first – then hear it later

  26. Wave Speed • Wave Speed = Frequency x Wavelength Speed = νλ Light = 3.0x108 m/s Sound ≈ 340 m/s (Faster than most jets)

  27. Hammering

  28. Instruments to sense light energy

  29. Instruments to sense sound energy

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